This region covers Bedfordshire, Buckinghamshire, Hertfordshire and Northamptonshire. And what a friendly and well organised group they are!
These regional days pack a lot in: traders’ stalls, a big bring and buy table and a raffle for guild funds, superb cake, show and tell of members’ quilts and, of course, talks.
The phenomenon that is Philippa Naylor
In the morning we were in for a treat. The speaker was international prize winning quilter Philippa Naylor. I have long admired Philippa’s exquisite, flowing whole cloth quilting, but I never realised what an absolute hoot she is. Her main message to the audience was that we should enjoy life to the full and that success does not depend on unique special talents or gifts. She told us that her success is down to dedication and lots of hard work. Anyone can achieve an outstanding standard of work, if you have the discipline and commitment. She says life is short, so do what you love and work at it until you become really good. She did also emphasise that having been born in Yorkshire helps, it gives you grit!
It was clear that Philippa knows how to remain connected to joy and fun which fuels her creativity and staying power. She entertained us in words and pictures with details of what she really loves in life. Family, her chickens and ducks, her flower and vegetable garden, her home, her county, beauty and nature. Hard not to smile just remembering how she conveyed her passion for life. And all of this shines through in her stunning quilts, several of which were on show.
River Ran Red Quilt
More modestly, the group heard a talk in the afternoon from me about my City and Guilds quilt inspired by the 19th Century Norwich Shawls. With added info on our dye garden and how to use grand teint plant dyes to achieve bright and fast colours on fabrics.
Here are some links I promised for anyone interested in learning more.
Aviva Leigh – now based in the Norfolk market town of Aylsham – is a tinctorialist and designer who has studied and promoted the history of Norwich textiles and recently presented her work for the Geoffrey Squire Bursary Award of the CT&A recreating dyed woven textiles from 18C Norwich pattern books.
Since the industrialisation of synthetic dyes most of the knowledge of plant dyes was lost in Europe until it was partially revived by craftspeople like Ethel Mairet and Later Jill Goodwin, Hetty Wickens, Jim Liles, Jenny Dean and many others. Jill Goodwin lists 140 dye plants alone in her book “A Dyer’s Manual”. Reading the books of these trailblazers has given me an almost obsessive interest in some of these plants – how to grow them, how they are related, what dyes do they have in common etc. In today’s plant dye world we seem to have concentrated on just a handful of key plants (such as Madder, Japanese indigo, and Weld) which give the best and most light fast colours. People still like to try dyeplant materials that are easily foraged and some of these produce good colours, but many are short lived. Personnally I think that foraging in an already over exploited environment is a practice that should be avoided if possible and I want to grow the plants myself, find out more about them, what they look like, how they grow, what sort of conditions they like, how closely related they are, what pests eat them etc. Natural dyeing is a step on the way to connecting with our precious environment and finding out about and growing the plants we use is another step.
Some while back I realised that Common Madder has a host of relatives, some of which are actually native to the British Isles. As you would expect with close relatives, these plants are similar in appearance and habit. They are all clambering or creeping plants with weak, square stems and thin spikey leaves which usually grow in whorls from the stems.
There follows a list of some of the experiences I’ve had with new plants this year starting with relatives of Common Madder. Where possible I obtained seeds and started them indoors in seed trays in March/April, planting out in May.
Dyers Woodruff – Asperula tinctoria
Dyer’s Woodruff in flower
I was unable to obtain any seeds for this madder relative so I was very pleased to discover a Scottish plant nursery (Poyntzfield Herb Nursery) selling the plants. In March, they sent a big bundle of bare rooted plants wrapped in sphagnum moss. But as we were then still experiencing freezing and wet conditions I potted up the thick red roots in some ordinary potting compost. Most of these have grown well but a few died after initial good growth. There remain a few which are struggling with yellow brownish foliage even though I planted them out in a variety of soil types. I’m not at all sure what the problem is. Dyer’s Woodruff is an attractive feathery plant similar to its relatives with two to four small thin leaves at intervals along its stem. Small white flowers appeared in June. Now in early August it looks as if a tiny few are developing seeds, which I hope I’ll be able to save. The roots are not as large as madder but they are quite respectable and I’m thinking that of all the new madder relatives we obtained this year this is the most promising. The books say it will grow in acid and alkaline soils and can also grow in partial shade. I’m testing this out.
Ladies Bedstraw – Galium verum
Ladies Bedstraw in flower
A clump of young Ladies bedstraw plants will grow into a cushion and then a carpet.
This plant is native to Hertfordshire and happily grows in chalk soil meadows. It will also grow in many other conditions, including poor sandy soils. The leaves are smaller than Dyer’s Woodruff but have whorls of six leaves at intervals along its stem, much like madder. This plant has grown from seed very robustly. I planted seedlings out in clumps of 15 to 20 creating very attractive cushions of feathery green foliage. These have grown into ground covering carpets with flower stems reaching 6-12 inches high, with tight clusters of pretty yellow flowers in July/August. It makes an excellent trailing plant and although the flowers don’t last long it would make an attractive contrast to some more showy flowers. In the wild this plant is very competitive and will happily grow in grassy meadows. Tended and watered it responds very well, producing long lasting carpets of foliage. Wild plant roots are thinner than Dyer’s Woodruff so I’ll be interested to see if cultivation makes a difference.
Field Madder – Sherardia arvensis
An agricultural weed, Field Madder, is a small creeping annual plant with thin roots.
This is a classic annual weed of agricultural areas producing small creeping plants with tiny pale pink flowers, leaf whorls of from 4 to 6 leaves looking very much like miniature madder leaves and large seeds which are produced very quickly. It’s difficult to see how this could have been used as a dye plant considering its small size, short life cycle and thin roots. The books say it was used, so I thought I’d give it a try. Seeds are not too difficult to obtain but do not readily germinate – they have a typical weed habit of staying dormant in the soil maybe for years waiting until the conditions are just right. They do produce a mass of roots so it could be worthwhile. I think that the key to obtaining an easy harvest would be to grow it in pots in good quality compost that could be washed away when the roots have grown. I do not know how much of a problem weed these plants are but they do seem to like growing with other plants which they use for support and do not do so well on their own. They are supposed to be good self seeders so we will see.
Devils Bit Scabious – Succisa pratensis
Rosettes of Devil’s Bit Scabious planted around an Alder Buckthorn sapling in a specially created acid soil bed. There are also some first year weld plants bottom right.
Devil’s bit scabious flower
This is a plant I’ve wanted to grow for a long time for its ability to attract bees and other pollinators. In addition, its pin-cushion-like flowers are a pretty lavender blue and open out in July to October at the same time as many of our yellow flowering dye plants. Growing some plants with a contrasting flower colour has been a bit of an obsession for us. Yellow is nice but needs contrasting colours to really bring it out so I was delighted to discover that the Devil’s Bit Scabious is also a reasonable dye plant, at least according to Jean Fraser in her book Traditional Scottish Dyes where she gives a recipe for greenish yellow with alum mordanted material. Intriguingly she also notes that according to Ethel Mairet the leaves of the Devil’s Bit plant also contain indigo, but I’ve read that before about Weld and that turned out to be nonsense. (I can feel an experiment coming on!).
The plant grows much like woad, producing a thick rosette of large leaves in the first year or two before flowering. It is a perennial but can, according to other accounts, suffer from getting crowded out by more vigorous plants. It is notoriously difficult to germinate from seed – out of about 100 seeds I only managed to get about 4 germinations and, on previous attempts, none at all. Fortunately the plant can be obtained from specialist nurseries and we got some very healthy specimens from Rosybee which have grown very well and two of these have just started to come into flower.
Shrubs and trees
Alder Buckthorn – Frangula alnus
Alder and Purging Buckthorn are often sold as hedging plants. They can be found growing in the UK countryside provided you know what they look like. And there is the rub! They look pretty much like a whole load of other small trees so part of the reason we decided to buy some saplings was to familiarise ourselves and be able to identify them in the wild. The nursery we bought the plants from (Ashridge Nursaries) were adamant that Alder Buckthorn could not be grown in our chalk soil so I have put plants in different soils and environments to see how they get on. They arrived bare-rooted in mid March, after the late freeze relented. I heeled them in compost in a sheltered spot on the patio at home until planting them out in April. So far the best growth has been achieved on the allotment, planted in a special “acid” bed made by piling up and digging in ericaceous compost to the light chalk soil. Second best growth is in a large garden planter filled with a mixture of ericaceous and ordinary compost. The last 2 were planted into a cleared grove of Blackthorn growing on chalk soil without any compost, or any watering for that matter. Needless to say these two have not grown much at all, but they are still alive despite the drought and alkaline soil, so we will see. The bark and leaves of this and Purging Buckthorn are usually cited as sources of yellows to dark brown dye stuffs with “sap” green coming from the unripe or ripe berries (different sources give different information). Of the two species, Alder Buckthorn seems to be the main dye plant but I have been unable to find any direct comparison. Another experiment that needs doing!
Purging and Alder Buckthorn roots are quite different. Black roots of Purging on left and red roots of Alder on right.
Purging Buckthorn – Rhamnus cathartica
Very similar in appearance to Alder Buckthorn but supposedly equally happy on acid or alkaline soil. I planted most of the saplings on chalk soil at my apiary and left them to fend for themselves. But I saved one sapling to try out in an acid bed, on the allotment (near the Alder Buckthorn) but it has not grown as vigorously and the leaves have gone yellow in places.
Both Purging and Alder Buckthorn are serious invasive pests in the United States and Canada and are banned in two US states.
Black or Quercitron Oak – Quercus velutina
Black Oak sapling
This is a large tree from central and eastern USA which became a very important commercial source of yellow dye in Europe in the 19th Century, even after synthetic dyes started to dominate. We have read a fair bit about this tree’s splendid history and that of the man who promoted it (Edward Bancroft – scientist and spy) and thought we would try and grow it mainly out of historical curiosity. Despite a warning found in one dye book that you could not grow it in the UK, we found a supplier in Cornwall (Burncoose Nurseries). So we are now the proud owners of a small sapling growing in a large planter in our back garden. It will be great to see if we can get some dye stuff from the inner bark but, let’s face it we might be long dead by the time the tree is big enough to harvest a branch or two!
Smooth Sumac – Rhus glabra
Smooth Sumac in flower
Of all the different species of Sumac, we decided on this North American one for several reasons. It’s perhaps one of the most decorative, it is wildlife friendly and also fully hardy. It has a high tannin content and the berries it produces are said to be edible. It can produce invasive underground suckers so we are growing it in a large planter. There are plenty of other sumacs growing in peoples gardens and in waste areas around Hitchin but it’s nice to have one right there in the back garden – no foraging needed.
Hopefully in a year’s time we’ll have some dyed samples to show how successful these new plants have proven to be.
Currently the main method of indigo extraction in use on internet Facebook pages is the 2 -3 day long soak in water. I believe this was the main method used commercially in the days before synthetic indigo wiped out the western market for natural indigo. Originally used to extract indigo from Indigofera tinctoria it is still used for small scale production in South Asia. The method is now used for Japanese indigo presumably because the traditional Japanese Method of composting the leaves is too large scale and time consuming for craft dyers. So it has been with some bafflement that I’ve seen the rise of this soaking method as I have always followed the Jenny Dean method which is even quicker.
We were introduced to plant dyeing through the pages of Jenny Dean’s “Wild Colour” and have used her recipe from this book for many years. It involves heating the leaves and can be done in two hours. Since we started to use this recipe we have tweaked it somewhat, discovering that there is no need to heat the leaves over 75 to 80°C to get maximum extraction. Another wrinkle is the need to allow the heated leaves to cool fairly rapidly. Large containers holding 20+ litres tend to cool too slowly and the indigo can be damaged. We did try one experiment when we cooled the extraction bath artificially but that was too quick and the results were very poor. An ideal extraction would be to heat about 1kg of leaves in 5 to 10 litres of water to 75°C and allow it to cool naturally over an hour. In our climate it will fall to around 40°C or less during that time.
So, now to the experiment which was a bit slap dash, but I am sure that it was systematic enough to have fairly good validity for a home dyer.
I picked just over 2kg of fresh Japanese Indigo of the Long Leaf variety which was showing no signs of any flower buds. This was divided into 2 lots of 1026g.
Long Leaf Japanese Indigo showing leaf curl – a result of prolonged hot sunny weather.
Hot Soak Method (based on Jenny Dean)
Once batch of leaves was added to a large pan with about 8 litres of cold tap water (20°C) and then gradually heated with constant stirring to 75°C. This took exactly one hour and at the end the leaves had lost all of their fresh green tint and had turned almost black. The water was a very dark grey (a lot darker than usual in fact and I attribute this to a higher than normal amount of indigo in the leaf – a result of the weeks and weeks of hot sunny weather we have had this summer).
The leaves were then left to soak for one more hour, after which there was an indigo bloom at the surface and the water had darkened further. The leaves were removed (by straining through old tights) and 4 tablespoons of household ammonia were added with an immediate colour change to dark yellow/green. The liquid was then oxygenated by pouring from bucket to bucket about 20 times during which the liquid darkened to a green black. A small quantity of the liquid (viewed from above in a white plastic cup) looked olive green.
Comparison of Hot and cold indigo extraction after 1 hour of soaking but before straining.
Cold Soak Method
The second batch of leaves was placed in a plastic bucket filled with about 8 litres of hot tap water (57°C). I used hot water because I did not wish to wait more than 24 hours. At this temperature the leaves become slightly cooked and release cell contents into the water quicker. The bucket was then set aside for 24 hours. After 1 hour the temperature had fallen to 44°C, the leaves were still quite green and the liquid was much paler and bluer than the hot extraction at the same stage. See image above.
After 24 hours the leaves were still greenish, although they had darkened somewhat. There was a lot of indigo scum on the top leaves. The liquid was grey with a blue tint. The plastic bucket was stained blue. Generally the results so far looked good, with much more blue visible than in the Jenny Dean method.
Cold indigo extraction after 24 hours. Lots of indigo bloom on leaves.
After leaves are removed, alkali (ammonia) added and liquid aerated.
Comparison of colour of water after extraction.
Colour of leaves after cold soak for 24 hours.
Empty plastic bucket used for 24 hour cold soak now stained with indigo.
The leaves were removed and about 4 tablespoons of household ammonia were added and the colour immediately changed to yellow green. The liquid was then oxygenated, by pouring back and forth between buckets about 20 times. During this process the liquid darkened until it was nearly black. A small quantity looked blue/green.
Both extracts were then heated at the same time in separate pans to 50°C, the ideal temperature for dyeing wool, and spectralite reducing agent (thiourea dioxide, thiox) was added (one and a half teaspoons) to each pan. They were then left for about 2 hours to give ample time for the indigo to be reduced. The pots were then reheated to 50°C and an identical skein of wool (Corriedale) was added to each. Both pots were then gently stirred to promote even dyeing and the skeins were removed after 20 minutes.
Initially the colour of the skein from the Jenny Dean (hot) method looked darker but on drying no difference could be detected.
Test dye showing relative strengths of dye bath from Hot and Cold extracted indigo.
The amount of indigo extracted appears to be the same for both methods. However, heating, cooking and stirring the leaves increased the amount of fine particulate plant material in the liquid which increased the amount of sludge in the bottom of the dye bath.
I should clarify I don’t use lime (as a combined alkali and flocculating agent) to obtain a dried indigo pigment from my dyeplants. Any indigo I don’t use straightaway for dyeing, I store as liquid sludges. But I can see that for people who do use lime, the cold soak is advantageous because the resulting indigo pigment would contain fewer impurities than the hot soak because the liquid extract after straining is purer. For myself I’m quite happy to continue using my modified Jenny Dean process as it is fast and reliable.
Out of interest I also decided to compare the Long Leaf Japanese Indigo to Woad. I processed a similar quantity of Woad leaf according to the 24 hour soak method in the experiment. Another wool skein was dyed in nearly identical conditions and the results prove to me that Woad can actually produce more indigo than Long Leaf Japanese Indigo.
Comparison of strength of indigo extracted from Long Leaf Japanese Indigo and Woad.
A note on alkalis
There has been a lot of controversy about which alkalis produce the best results. I have tried most of them and found that what is important is the pH not the exact chemical used to get there. Washing soda is the weakest and produces very poor results. Household ammonia is excellent and relatively safe, provided you don’t get it on your skin or breathe it in. Calcium hydroxide (lime) is good and has the added benefit of soaking up the indigo precipitate and settling it to the bottom fast (flocculation). Sodium hydroxide is also good but is very corrosive – a danger to skin and textile.
Whenever using strong alkalis you must take safety precautions: wear gloves; avoid splashes; don’t ever add water to dry alkaline powders or granules, add the powder to water; label colourless solutions and store safely; never leave sodium hydroxide solutions unattended for curious animals or children to explore (it is colourless and odourless and very corrosive indeed).
by Ashley Walker Copyright August 2018 Banner photograph copyright Sharon Cooper
On the 9th August, after two months with barely a drop of rain, the heatwave and drought in the South East of England may finally have come to an end. Despite regular watering the unnatural weather has taking its toll on our dye plants. For the first time our woad plants are being eaten by Cabbage White butterfly caterpillars (Large White Pieris brassicae and Small White Pieris rapae) and more recently by flea beetles (genus Phyllotreta). I guess the critters were getting desperate to find plants with a bit of juice in their leaves. The weather is having an impact on me as well, I have to water the indigo nearly every day and keeping the rest of the garden needs water too so I’m spending hours each week that I’d rather be spending on writing or dyeing.
This is the first part of a two part post on observations of the dye plants in our garden. This one deals with the plants we have been growing for more than a year. The second part will cover new plants.
European Woad – Isatis tinctoria
These Large White caterpillars managed to eat the whole woad leaf, leaving only the midrib behind.
We have grown Woad for about 12 years now and for the first time our plants have been attacked by caterpillars and flea beetles. This makes a change from the usual small black slugs which put a few holes in the leaves but seldom do any serious damage.
A cluster of Large White butterfly eggs on the underside of a woad leaf
Shiny black small Flea Beatles can slowly chew their way through a woad leaf leaving it like a sieve.
Woad flower spike August 2018 – from seed to flower in one season as a result of pampering.
I expect that the extraordinary hot weather is to blame with the butterflies and beetles probably acting in desperation. Although the flea beetles appear to thrive, the caterpillars have had a much harder time digesting the unpalatable leaves and most of the newly hatched critters have simply died, leaving a few small holes in the leaf. Only one plant had its leaves reduced to its midrib but even this one will survive as it is now putting out new growth. Interestingly it appears to be only the plants I have watered which are being eaten. There are a few plants which never get watered and these are looking fine.
A few people have asked about growing Woad in tubs or containers and this year we’ve had a few in containers ourselves and this has revealed a problem. One of our plants grown in a container in good compost and watered and fed regularly has grown large and is currently putting out a flower spike which will drastically reduce the amount of indigo in its leaves. Its very unusual to see Woad flowering in August so I can only assume we have pampered it too much – given it the ability to grow large enough to flower in one season. So if you are growing Woad in containers don’t give them too much fuss!
Chinese Woad – Isatis indigotica
Chinese Woad – about as big as it gets before flowering
Planted out in April these Chinese Woad immediately produced flower stems
We have been growing this for two years now, desperately trying to find out how to stop it flowering a few months after planting. From what I’ve read I’m in good company and this is the chief reason Chinese Woad has not caught on as a source of indigo, despite the fact that it could potentially produce as much dye as Japanese Indigo. Some of the literature indicates that botanists think Isatis indigotica is basically just a variety of tinctoria (European Woad). However, if that is so it has evolved away from tinctoria to a considerable extent. Indigotica is clearly adapted to a much warmer climate and although still nominally a biennial it behaves much more like a half hardy annual. It will flower at any time of year, even in winter, so its rosette stage is always very short and the plant never gets very big. The leaves are a paler blue-green than European Woad and its yellow flowers will continue to be produced throughout the year provided the plants are watered and taken care of. Once the plant starts to flower the larger rosette leaves die off leaving only small leaves on the plant which are probably no good for dyeing. According to the Handbook of Natural Colorants, indigotica will be triggered into flowering if the night time temperature falls below 5°C, which makes it almost impossible to grow the plant to any respectable size here in the UK. Even in Mediterranean climates the plant can only usefully be grown in the Summer. From my experience the plant will flower even if you just look at it the wrong way so I’m coming to the conclusion that it’s not worth the effort. It does grow very quickly however and if you were to grow it en masse and harvest the leaves before it flowered it might just provide a return for your efforts.
Another problem with Chinese Woad is its susceptibility to pests. Caterpillars and aphids like it very much and can easily destroy your plants. And you guessed it, significant insect damage will also trigger flowering. In a mad moment I decided to see if Chinese Woad tasted any nicer than European Woad. But the taste test settled nothing, both plants are extremely bitter and fiery. I obviously don’t have the finer tastes of Cabbage White butterfly caterpillars!
Japanese indigo – Persicaria tinctoria
Long leaf variety of Japanese Indigo with curled leaves to protect itself the prolonged hot sun of 2018
This year we are growing the same three varieties as last year – Long Leaved, Broad Leaved and an Intermediate Leaved white flowered variety. There appears to have been no interbreeding from last year. This year the difference between the long leaf and broad leaf varieties is stark. The Long Leaf plant is very vigorous with dark green leaves. The Broad Leaf variety took a long time to get going as usual and suffered from its leaves turning red. I was initially confident that the red colour was partly due to the hot sunny weather we were having in early summer – the slow growing plants were getting roasted. But after a good feed (with chicken manure pellets) the plants started growing quickly with the new foliage a nice mid green despite the continued hot sunny weather. So a bit of a chicken and egg situation: was it the lack of fertilizer that caused the leaves to redden or simply that the young plant leaves, growing slowly, were getting a longer exposure to the hot sun? The Long Leaf variety reacted differently to the hot sun with leaf curling , something I had seen last year but only on plants grown in the greenhouse.
A bed of intermediate White flowering Japanese Indigo.
Newly planted out Broad Leaf Japanese Indigo with sun reddened leaves.
Thus far we have only harvested the Long Leaf variety and used it in a little experiment comparing Jenny Dean’s extraction technique with the more often used long soak in cool water. The results will be written up in a later post. What I have also noticed is that we are currently getting a considerably better production of indigo from Woad than the Long Leaf variety of Japanese Indigo. Woad is well known for giving better results when the weather is hot and sunny. If the climate change predictions are correct and we continue to have hot summer weather then I think we would be better to return to growing mostly Woad. The Long Leaf variety of Japanese Indigo produces the least amount of indigo dye of the three varieties (see comparison here) but it does produce larger plants so perhaps still produces an equivalent amount of indigo per square metre.
Madder – Rubia tinctorum
Once again this year the madder plants are producing masses of berries. This is the third year running. In the previous 10 years or so the plants produced only a few. I have no explanation as to why this is. I’ve grown plants in different soil, in planters and in the ground and all plants are doing the same. A result of the weather?
Madder plant obtained from Southwark Cathedral in early 2018.
This year we obtained a new madder plant sourced from Southwark Cathedral dye garden. The plant is quite different to plants I have been growing up to now (all of which were derived from a single seed over 10 years ago). This new plant has paler leaves with a different shape and it flowers about 3-4 weeks later. It will be interesting to see if the root yield is also different. I’m pleased to have been able to increase the genetic diversity of our madder as I’ve always propagated by root stem cuttings or from seeds from my own plants.
Wild Madder – Rubia peregrina
Wild Madder in flower – Early July
We’ve been growing this plant for nearly three years now. It’s an evergreen but the tops do not appear to be totally hardy in the UK climate and were damaged by the winter frosts. This is the first year in which the plants (originally obtained from a wild flower nursery) are starting to look a bit happier. They are putting out new shoots from underground stems and flowering for the first time. It remains however a very slow growing perennial and I think it will take longer than Common Madder to produce a good root harvest so we are leaving it for another year.
I was given some seed from a friend from some wild plants growing on the south west coast which nearly all germinated though it did take well over a month before the first shoots appeared.
Saw wort – Serratula tinctoria
Saw-Wort plants with yellowing of leaves.
A self seeded plant with dark green leaves growing next to the transplanted ones with yellow leaves.
This native plant continues to be disappointing. Not only do the plants remain small but about half of them suffer from bad yellowing of the leaves once planted out in the garden. I have tried practically everything to remedy the problem – fertiliser, Epsom salts and seaweed extract. There are some self-seeded plants which look very healthy so I do wonder if the roots are somehow getting seriously damaged during transplanting. It also remains likely that there is something wrong with the soil itself as other plants (Genista, a red scabious and a Purging Buckthorn shrub) are similarly affected.
A comparison of our main yellow dye plants. Top is Weld, Bottom Right is Genista and Bottom Left is Saw-Wort
We did try dyeing with the Saw Wort this year and obtained a good buttery yellow. We were hoping it would be a nice lemon yellow like Weld and Genista so were a bit disappointed with that too.
Bumble bee on single type dahlia grown from seed.
Dark Red Dahlia giving pinky purple and greens. Possibly “Nuit d’Ete” or “Black Cat”
The colour of Dahlia flowers has an effect on its dye but we did not appreciate by just how much until this year when we tried using some deep red flowers to dye with. We obtained nothing like our accustomed strong yellows with acid pH and strong orange with alkaline pH. This time we got green with alkali and blue/purple with acid indicating that the dyes in this dark red flower were the same as you find in red cabbage and some other red flowers. These dyes, although very pretty, are not light fast. Over the years of growing Dahlia we have narrowed down the varieties that produce the best results for the home dyer. These are yellow or orange double flowering pom pom types. The pom pom flowers are longer lasting and produce more dye – some pom poms are very large and yield a lot of dye but bees and pollinators are unable to assess the nectaries. We have tried to stay away from these but there’s no doubt they are the best for dyers.
Tansy – Tanacetum vulgare
Tansy needs regular watering for healthy plants.
Often used by Scottish dyers as a source of yellow dye this plant has been growing in our garden for several years now but largely unused because the plant wasn’t very vigorous. There was never enough plant material to harvest and the flowers were disappointing. This year we planted a bed of Japanese indigo alongside so the Tansy benefitted from being regularly watered. The resulting Tansy flowers have been lovely so if you’re growing them keep them watered for best results.
Perennial Coreopsis – Coreopsis grandiflora varieties e.g. Golden Joy, Sun Ray, Early Sunrise
Perennial coreopsis – plant breeders benefitting the plant dyer.
Bright orange on alum mordanted wool blanket.
These are double flowering perennials with deep orangey yellow flowers which produce a lot of dye. They are not as hardy as the growers would have you believe as half our plants died during the winter and only a few have recovered enough to put on a good show this year. However, many can be easily grown from seed so are not too expensive to grow. They make excellent bedding plants and produce a fabulous orange dye from the flowers. An example of the plant breeders unwittingly aiding the home dyer.
Dyer’s Alkanet – Alkanna tinctoria?
Alkanet root. Bottom tip has had thin outer black bark removed revealing the dissapointingly white root.
This is the third year of growing and though I have not tried to extract any dye from its roots I am deeply disappointed to find that the roots are not red as they should be. I was suspicious as soon as I started to grow the plant from seed bought from the German Company Rühlemann’s. The plant seemed too vigorous with over large leaves and not hairy enough, but I persisted with it until it flowered. The flower shoots were tall (up to about a metre high) and not at all like the creeping wild flower growing around its native Mediterranean. The flowers when they finally appeared were the only part of the plant that looked like the pictures of Alkanna tinctoria seen all over the internet but the roots? The roots were white!
Doing some reading around this ancient dye plant I find that its qualities as a medicinal plant derive solely from the coloured substances in the root which were used as a dye, cosmetic and bio stain so you can imagine the way I feel after lavishing attention on this plant for the last three years only to find the roots are white! Recently I discovered one internet comment on the plant that says the cultivated version of the plant does not produce as much dye as the wild type. Well that’s some understatement. Of course it is possible that lavishing attention on the plant was entirely the wrong thing to do and I should have left it alone but it seems more likely that the growers have simply selected the seed year after year from the largest prettiest plants and in so doing have bred out the qualities that gave the plant its historical value.
Just to confuse matters Alkanna tinctoria has been and is also known as “Anchusabracteolata, Alkanna tuberculata, Alkanna lehmanii, Lithospermum lehmanii”, and has been given various common names as follows Alkanna Radix, Buglosse des Teinturiers, Dyer’s Bugloss, Henna, Orcanète, Orcanette, Orcanette des Teinturiers, Orchanet, Radix Anchusae. Rühlemann’s who sell the seed are now calling it Alkanna tuberculata. There is certainly confusion on the identity of all these plants. Are they all the same or not. If there are any botanists out there who can get to the bottom of this please please get in touch!
Philip John and Luciana Gabriella Angelini – Indigo – Agricultural Aspects. Chapter 7 of Handbook of Natural Colorants Edited by Thomas Bechtold and Rita Mussak. Wiley Series in Renewable Resourses. (Available as free download).
Rühlemann’s This German herb plant and seed supplier has a number of dye plants for sale including Chinese Woad and Long Leaf Japanese Indigo but it is primarily interested in the medical properties of the plants it sells and I get the impression they know little about plant dyeing.
2018 is turning out to be our most successful yet.
The year began with our good friend Brian Bond joining us to deliver a two day workshop in Ipswich in late January with the International Felters Association (see above). Susan was involved in much mordanting in preparation. This was our second major plant dye workshop away from home, and dependent on friends or family to help us with transport. Hard work packing an ‘all singing all dancing’ workshop and the three of us into a single hatchback vehicle (albeit a large one, thanks Brian!). Quite stressful but very well worthwhile, as the students were terrifically motivated and created a full palette of wonderful colour on the finest merino tops.
Also in January we had confirmation that Southwark Cathedral had invited the London Guild of Weavers, Spinners and Dyers (WS&D) to demonstrate plant dyeing as part of London Craft Week in Mid-May. Susan was asked to coordinate the project, having held a successful mini natural dye demonstration there as part of the biennial London Guild exhibition last November.
Preparations for all this activity took place mostly in the winter and early spring when the weather was too cold or wet to work outside on the dye garden
In between scoping and planning the London Guild event at Southwark, Susan gave talks on plant dyeing to the Chelmsford Embroidery Guild, on the red dye from madder for the Cambridge Guild of Weavers, Spinners and Dyers and, closer to home, a talk on the horticulture of dye plants for the Wymondley Gardeners Group. Had the snow in early March not intervened there would have been another talk on the history of Norwich Dyers to region 7 of the Quilters Guild.
The Shard overshadows our colour splash at Southwark Cathedral
Susan spent much of April mordanting and test dyeing fabric and yarn for the London Craft Week event, which was to be held outdoors in the Churchyard in mid-May. Fortunately the weather improved and we were blessed with two sunny breezy days. With help from textiles graduate Hannah Sabberton, Susan and I carried Hitchin grown fresh woad and dry Weld, Indigo dye solution, mordanted fabric yarn and fleece, samples, display materials and goodness knows what else (kitchen sink comes to mind!) on the train and bus into Central London at rush hour. We are resourceful public transport travellers with trolleys and backpacks and all arrived safely! Mercifully all the pans and heaters had been supplied by London Guild members based not too far away (thanks to Penny and Diane). Also there were many, many lovely dyers from the Guild who shared the demonstrating. All told there were twenty two volunteers across the two days. We spoke to people from all over the world, from London and other parts of the UK. Tiring but very satisfying to see the rainbow of colours we achieved with just the three medieval ‘grant teint’ plant dyes: Madder, Weld and Woad.
Susan managed to escape a couple of times down to the British Library where she loves to do research on the history of dyeing and in particular the 19th Century “Norwich Red”. An article to be published in the Autumn issue of “The Journal of Weavers, Spinners and Dyers” will detail her findings so far. We have also been asked to write an article on growing dye plants with a particular emphasis on small gardens and container growing. This should appear in the next issue of “British Fibre Arts” along with a profile about ourselves. The Editor Rainy Williamson made us think about what we do and why we do it. I was particularly reminded that many people do not have access to a garden or allotment and may only be able to grow dye plants in small spaces. I immediately set about making and planting up some large-ish containers with suitable dye plants to see how they responded. And then we got to thinking that apart from a couple of small demonstrations and the regular workshops for our local guild we’ve never made an effort to share our skills in plant dyeing with the local population. So Susan quickly got on the phone and asked the Hitchin Festival organisers if they still had some slots left in their programme and lo and behold, (thank you Keith) we were found a slot in the programme.
Results from the green overdye experiment done at the Herts Guild of Spinners Weavers and Dyers Workshop
Meanwhile we had another workshop for our local Guild in North Herts to get ready for. This was based around an experiment investigating the notion that a better green is obtained if wool is dyed first with indigo and then weld (yellow) rather than the other way round as we have traditionally done it. Various accomplished plant dyers had reported this finding and we wanted to check it out. The workshop produced some fantastic greens and, somewhat to our surprise, the blue overdyed with yellow did indeed produce the best green.
While all this has been going on I’ve been working hard on the Natures Rainbow dye garden, getting it into shape to satisfy the North Herts District Council allotment inspector (Grounds Maintenance Monitoring Officer). Because we are growing a most unusual set of crops some of which look remarkably like weeds we
Madder is closely related to the weed Cleavers or Goosegrass. It looks and behaves much the same but is altogether larger in stalk and leaf and has berries instead of hard seeds.
The Natures Rainbow allotment plot in early June.
have to make the plot look as tidy as possible. Madder for example is a close relative of the weed Cleavers and has the same sprawling habit and Weld is generally classified as a weed anyway. In addition, we leave our second year Woad plants to go to seed, so we have stock for the following year and this too raises eyebrows.
Dyers Woodruff in flower
We also decided early on this year that if we are going to continue giving talks and writing articles about growing dye plants then we need to expand our experience and grow some of the more unusual dye plants so we sent off for more seeds including Chinese Woad, Wild Madder, Field Madder, Ladies Bedstraw, Blood Root and where we couldn’t get seeds we ordered plants. These include Dyers Woodruff, Black Oak, and Smooth Sumac (Rhus glabra).
Our new Black or Quercitron Oak Sapling. The inner bark of this North American tree produces the dye quercitrin which for a while was a major industrial source of yellow dye. Of course it will be many years before we can harvest any bark from this specimen!).
Honey bees are particularly fond of Weld
As a beekeeper I’m also very interested in growing plants that are also good for all kinds of bees so I’ve been very gratified that many of our dye plants are also fantastic bee plants too, Weld and Japanese indigo are two of the best.
Smooth Sumac from North America, the dried leaves of which contain 25-27% by weight of tannins.
Look out for more blogs detailing some of the events mentioned here but you might have to wait until things calm down a bit before we get time to write them!
Follow up to Cambridgeshire Guild Talk 28 April 2018
Getting the best reds from Madder sometimes seems more of an art than a science. On a cold wet late April day, I gave a talk on the subject to the Cambridgeshire Guild of Weavers Spinners and Dyers. They are a very active guild and judging by how quickly the madder and madder root cuttings disappeared from the sales table afterwards, gardens and allotments across the region will be featuring more madder in the future! Thanks to Camilla for inviting me and for Sue’s lift to and from the station. Also thanks to whoever baked the lemon cake we had with tea afterwards. It was divine.
As follow up, here are some pointers for supplies and books I promised to share online.
There are many modern books on plant dyeing which are approachable for beginners.
Although filled with inspirational images and ideas, the reliability of plant dyeing advice varies dramatically. My current favourite which is most certainly well researched and reliable is:
Kristine Vejar (2015) The Modern Natural Dyer, a comprehensive guide to dyeing silk, wool, linen and cotton at home published by Stewart, Tabori & Chang.
Kristine is based in California and runs a business with a blog “A Verb for Keeping Warm”
Debbie Bamford, a pre-eminent historical dyer who sells plant dyed cloth, yarn and threads at re-enactor markets and also via etsy shop. She trades as Mulberry Dyer and is active on social media.
Jenny Dean Doyenne of Natural dyeing in UK.
Her landmark book is Wild Colour (2010) but all her books are excellent.
Robert Chenciner’s book ‘Madder Red, A History of Luxury and Trade’ (2000), Curzon Press well worth getting from a library if you can’t find an affordable copy for yourself.
Jim Liles’s book ‘The Art and Craft of Natural Dyeing, Traditional Recipes for Modern Use’ (1990) University of Tennessee Press. Comprehensive recipes and valuable tips for improving mordanting with aluminium acetate. Contains the long method for extracting all the goodness from madder root (p106).
Ethel Mairet (1916) A Book on Vegetable Dyes
This contains the quick method for madder on wool recipe 1 on p99. But WARNING do not go anywhere near recipe 2 on p100, as this uses chrome mordant now known to be carcinogenic. Likewise tin mordant is toxic. For a very good discussion on toxicity of mordants see Carrie Sundra’s blog https://alpenglowyarn.wordpress.com/2014/11/11/mordants-and-natural-dyeing-the-great-debate/
Edward Bancroft’s two volumes “Experimental researches concerning the philosophy of permanent colours “ Vol I and Vols I&II
Other key references
Dominique Cardon (2007), Natural Dyes: Sources, Tradition, Technology and Science , Archetype Publications
Judith Hofenk de Graaff (2004) The Colourful Past, Origins Chemistry and Identification of Natural Dyestuff, Archetype Press
Thomas Bechtold and Rita Mussak (Eds) (2009), Handbook of Natural Colorants, Wiley
Suppliers of Mordants and Natural Dyes
George Weil/Fibrecraft for plant dyes and mordants; especially aluminium acetate mordant for silk and vegetable fibres. Sells Iranian madder. P&M Woolcraft unfailingly friendly and efficient with good prices (but Pauline has very sadly just passed away, so Martin may not be able to fulfil orders with the usual turnaround). Wild Colours sells madder and mordant and provides lots of information
Seed and Plant Suppliers for madder and other UK plants that give red
Poyntzfield Herbs – a great little company from the Black Isle in NE Scotland. Sells dyers woodruff and sweet woodruff plants. Their website is a bit low tech but they respond promptly to emails and are very helpful. Our plants arrived safe and sound when we put in an order earlier this year and are doing well.
Emorsgate – specialists in wild flower seeds – you can order in bulk for sowing whole meadows! We sourced our ladies bedstraw seed from here.
Saith Ffynnon – another good small supplier for wild flower and other useful plants. Sell seed and plants. Stock varies according to season.
When we first became interested in growing and using dye plants we came across an entry in “Traditional Scottish Dyes and how to make them” by Jean Fraser. This seemed to us to be very exciting because it offered a tantalising alternative blue dye to Woad indigo.
Page 69 from Jean Frasers book – Traditional Scottish Dyes and how to make them.
We immediately set about obtaining some seeds which were readily available as Elecampane is a popular garden flower and ancient medicinal herb. Our first lot of seedlings were all eaten by slugs but the second batch (protected until they were larger) survived to produce two small beds.
It took a number of years for the plants to reach full size but by this time we had realised that the likelihood of obtaining blue from the roots was very unlikely and we had discovered Japanese Indigo so did not think it worth even trying. We kept the plants because every year we are rewarded with a sunny display of glorious yellow flowers which act as magnets for bees of all kinds. These tall plants with giant leaves are low maintenance and just take care of themselves.
Honey bee on Elecampane flower.
The Dye garden has grown over the years and we are getting to the point that every plant species we grow has to justify its presence by being a proven source of plant dye. But still, the mystery of Jean Fraser’s entry stuck in our minds so this year I decided to give it a go before the plants started to grow.
Three of the incomplete “no details or quantities given” recipes mention whortleberries and one recipe Elder (presumably berries) as additives to improve the colour. We know by now that most black berries can give pinks, lilacs and mauves with a good alum mordant but they are not lightfast, iron mordants are best at prolonging the life of fugitive dyes and the fourth recipe mentions iron so we thought it worth obtaining some whortleberries . What are whortleberries?
Wikipedia suggests they are one of three possible members of the Vaccinium family:
All three plants grow commonly in Scotland but we think it is a reasonable guess that the name refers to the bilberry V. myrtillis or uliginosum as vitis-idaea is a red berry. The closest source of berries we could get hold of were supermarket blueberries (probably Vaccinium corymbosum). Not as good as our native bilberries as they only have a blue black skin and internal pale green flesh. Our native species are blue/black throughout.
Initially we tried a number of variations:
Fresh chopped and bruised roots heated with and without blueberries
Fermented chopped and bruised roots with and without blueberries
Samples of unmordanted, alum mordanted and iron mordanted wool were added to each of the dye pots (the root and berry material were not removed).
The roots of elecampane are white with a yellowish skin and black bark which is not attached to the root and is easily washed off. There appears to be no colour in the root at all!
Elecampane cut root
Because of this lack of colour we had long suspected that the only possible source of colour would be from tannins in the root reacting with the iron mordant to give a grey. We suspected that in Scotland grey was often called blue and with the addition of some whortleberries a bluish grey could be obtained though it would fade to grey over time. As there are many other sources of tannin in the dye plant world we were sceptical that Elecampane root would give us anything worth having.
The results were fairly conclusive in that the only significant colour change occurred with the iron mordanted wool where a silvery grey was obtained from the fresh root and a yellowish grey from the fermented root. The unmordanted wool stayed white and the alum mordanted wool turned a very pale yellow. The addition of blueberries made little difference.
Right: iron mordanted wool in fresh root dye bath. Left: Iron mordanted wool in fermented root dye bath.
On the left cut root treated with iron mordant. On the right untreated root.
Painting an iron mordant solution onto cut plant material usually shows up the presence of tannins fairly rapidly but sometimes it takes a few hours to get a colour change. The elecampane root had to be left overnight before the change seen here on the left took place. Other additives mentioned in the recipes are salt and ash. Dipping a cut root in salt had no effect but adding a tiny amount of sodium hydroxide (an alkali in wood ash [lye]) to the cut root turned it immediately yellow and after 24 hours a yellowish dark grey. We did not use any of this alkali in our experiments as we were particularly interested in obtaining a neutral or blue grey but it looks like adding the alkali could aid in getting a darker colour.
Once we were happy we could get this neutral grey we went ahead with dyeing a large skein of hand spun yarn (about 100g) mordanted with 1g of ferrous sulphate*. This was added to a dye bath made from about half a kilo of chopped and bruised Elecampane root heated to around 90°C and left for one hour then strained to remove the solids.
100g skein of hand spun iron mordanted wool dyed with Elecampane root.
OK, so no blue, but a good neutral grey is hard to obtain as most tannin rich plants have additional dye stuffs and the greys obtained are tinted with yellows or browns. Elecampane is almost free of any of these contaminants. As any designer will verify grey has the ability of amplifying adjoining colours making them seem brighter than they really are. A dye garden without a source of grey would not be complete so the Elecampane stays!
Elecampane in full flower
*The iron mordanting is done according to Liles method using the same quantity of oxalic acid as ferrous sulphate. The Oxalic acid prevents the iron from oxidising from the yellow-green ferrous sulphate to orange ferric oxide (rust).
I am passionate about working with cloth and yarn dyed from plants you have grown yourself.
I gave a talk yesterday to the Chelmsford Embroiderers’ Guild.
I had a lovely evening. Thanks to Angela and June for inviting me and for your hospitality.
As follow up, here are some pointers for supplies and books I promised to share online.
Mordants and Natural Dyes Earth Hues for extracts George Weil for plant dyes and mordants; especially aluminium acetate mordant for silk and vegetable fibres P&M Woolcraft very friendly and good prices Wild Colours sells woad powder, dyes and provides lots of information Fiery Felts I forgot to mention this supplier in the talk but Helen is very good for dyes especially dried flowers hard to obtain elsewhere. Her booklet on indigo is also excellent.
Dyed threads as well as dyes and mordants Renaissance Dyeing – based in France Mulberry Dyer run by Debbie Bamford, a pre-eminent historical dyer who sells at re-enactor markets and also via etsy shop.
Books and blog
Jenny Dean Doyenne of Natural dyeing in UK. Her landmark book is Wild Colour (2010) but all her books are excellent.
Women’s Work: The First 20,000 Years Women, Cloth, and Society in Early Times (1996) by Elizabeth W Barber
The Story of Colour in Textiles (2013) by Susan Kay-Williams
Fitzwilliam Museum Cambridge Sampled Lives till 7 October 2018
In January two years ago I ran a plant dye workshop for Region 5 of the International Feltmakers Association. One thing leads to another and … by way of the IFA AGM last Spring, I was invited to run a similar workshop this January for the Region 7. And what a delight it was!
Thank you to Sally Sparrow for organising the event.
With my friend Brian’s most excellent vehicle (I don’t run a car), and not a little anxiety as to whether I had packed everything we needed, we installed my dye studio in a scout hall in the outskirts of Ipswich for the weekend.
The venue was large and well appointed with power sockets for my preferred heat sources – portable electric induction heaters (you can see them in the background in the picture above).
By the end of the weekend nine enthusiastic participants had applied a good palette of natural colour onto nearly 2kg of pre-mordanted fine wool and silk. If you would like to know more and see some great photos, check out Kim’s blog at flextiles here and here. Kudos to Kim, for the excellent write up!
We used home grown madder for pinks and reds, home grown weld for acid yellow and for blue we used bought in woad powder and natural indigo (because at this time of year you can’t use fresh leaf). We also added in some oranges from dyer’s coreopsis and warm yellows from dyer’s chamomile, both from stock of our home grown, dried flowers.
Here are just some of the colours we obtained.
My aim was for people to get lots of hands on experience working with the dyebaths, to be free to spend most time on the colours that most interested them and get some theory and tips on good practice. I also like to make sure everyone goes home with enough fibre to use in a project. And finally, because I can’t resist the technical detail, there are handouts to read later.
The workshop couldn’t have run without my two helpers. My partner Ashley ran the indigo vats at one end of the room while I set up madder and weld dye pots at the other. Brian Bond, a longstanding friend and collaborator, was invaluable as all round helper.
For inspiration, Brian brought along his glorious plant dyed and hand spun yarn and knitted garments to display. Ashley brought his current work in progress – darned squares of which he needs to make 144 to complete a blanket. And I set out my collection of fabric and thread samples.
This kind of workshop has long been a regular feature of my local Spinners Dyers and Weavers Guild. We usually hold these events outdoors on a long summer’s day which works really well for rinsing and drying. I’m looking forward to running the next plant dyeing day for the North Herts Guild of Spinners Dyers and Weavers on Saturday 26 May 2018.
Contact me if you are interested in hosting a plant dyeing workshop. I am open to designing events to suit specialist audiences.
Note on blue: We were using a combination of commercially produced woad powder and natural indigo. To save time at the workshop, these were made up into separate pre-reduced stock solutions. We discovered that the woad powder was considerably less concentrated than the natural indigo. As a result the woad stock solution was over-reduced. The natural indigo produced some very dark blues (see below). Whereas the woad vat was over-reduced and it wasn’t possible to apply a deep colour, no matter how many dips we did. We plan to do a controlled experiment comparing the strength of different commercially available woad powders – so check back for more details.
This year I had planned to carry out a tightly controlled experiment to look for variation in the amount of indigo produced by three fairly distinct strains of Japanese indigo. However due to a prolonged and still undiagnosed illness, my plans were thwarted and the experiment did not work out quite as I had hoped. However, on 12th and 13th October 2017, with help from Brian Bond another keen plant dyer, I did manage to complete a test of the three plants although the results are not directly comparable due to different planting times and maturity of each variety.
Broad or Rounded leaf indigo
Round or wide leaved Indigo. Directly sown bed
Grown from seed originally from the USA (from fellow natural dyer Pallas Hubler in Washington State on the west coast) who sent a few seeds over to Brian in 2013. We have been growing and saving seed from this strain ever since so it is possible that it has become adapted to growing in our soil.
Late flowering (October into November)
Compact short flower stems
Wide short or rounded leaves
Foliage pale to mid green
Easily damaged by high nitrogen levels in the soil. Grows poorly in cool overcast weather.
Long leaf indigo
Long leafed Japanese Indigo in full flower.
Seed for this was obtained from the German supplier Rühlemann’s. Unfortunately this was in full flower by the time I was able to harvest it for the test and from previous experiments I know that once indigo has committed itself to flower production the amount of indigo in the leaf falls dramatically.
Large long pointed leaves
Long delicate flower stalks
Early flower (September-October)
Dark green leaves
Very tolerant of high nitrogen in the soil and generally more robust.
An in-between white flowered strain
Intermediate white flowered Japanese Indigo
Intermediate strain of Japanese Indigo with white flower.
The seed was obtained from Lisa George Fukuda a fellow plant dyer in Guernsey who had it originally from Teresinha Roberts at Wild Colours
Unfortunately this was planted out late in the year (August) so as yet I know little about its habit as there has not been enough time for it to grow to full maturity.
Easily damaged by high nitrogen fertilizer.
Mid green leaves
Quickly bushes out, highly branching.
All three strains were grown on the Natures Rainbow allotment in Hitchin in a chalk soil with a strong application of Fish, Blood and Bone plus some chicken manure pellets.
Leaves from all three strains.
Rounded leaf Japanese Indigo growing with the Long Leaf strain in the greenhouse. Here they look like two completely different species.
After stripping the leaves from the freshly cut indigo stalks, 220g of leaves from each strain were slowly heated from room temperature to 80°C in stainless steel pans with 4 litres of tap water. The pans were stirred at short intervals throughout. Note: the weight of leaves was determined by the amount of the long leaved strain that I could harvest from shoots that had not yet come into full flower as I wished to minimise the effect of flowering on indigo production. The amount of water in the pans was deliberately large as I wished the final colour to be on the pale side as variations in pale colours are easier to distinguish. More water also means the pot is easier to stir before the leaves are cooked.
Heating to 80°C took about 35 minutes. The pans were then taken off the heat and allowed to cool, free standing in the air for 1 hour. (The air temperature was appoximately 20°C).
Intermediate Japanese Indigo extraction bath with container of liquor to show gray colour. Photo taken just after pan was removed from the heat.
At this point no difference could be noticed between the different pans. The liquor in each pan being a pale greyish blue in each case.
After one hour the leaves were removed by straining through an old pair of tights into a large plastic bucket. Half a cup of household ammonia was then added to the liquor. Taking care not to breathe in hot fumes, this liquor was poured back and forth from bucket to pan 10 to 15 times to aerate and oxidise the indigo precursor to indigo. The colour of the liquor changed from grey to yellow green, with the round leaved plant giving the darkest colour change and the long leaved plant the least. This is a good indicator of how much indigo is present in each pan.
Once oxidised to indigo, the liquor is now in a stable form and can be left for long periods without any loss of indigo. The reduction vats (indigo dye baths) were set up the following day as follows. The pans were heated to 50°C, one level teaspoon of Spectralite (Thiourea Dioxide) was added to each pan, gently stirred in and left for 30 minutes for the indigo to reduce to its soluble form. Identical weight skeins (26g) of wool were added to the baths at 50°C and left for 20 minutes before removal and oxidation in the air. The dye baths were kept in a hay box to maintain constant temperature during the dyeing.
First results showing a surprising difference in colour obtained
The long-leaved plants (left) were disappointing only producing an ice blue colour. The white-flowered intermediate-leaved plant gave a slightly deeper shade but still pale (centre). The round-leaved plant produced a respectable light blue (right).
The poor results for the long-leaved plants was understandable because of their flowering state, however I was surprised the colour was quite so pale. The good results for the round-leaved plant was a real surprise as I had become convinced these plants would not be the best. Overall the pale colours made me worry that I had not optimized the process and I decided to repeat the experiment for the round-leaved and intermediate-leaved white-flowered plants (I had no more of the long-leaved plant so I could not replicate this one).
On the second run I made one change which was to slow the cooling of the extraction bath after reaching 80°C by placing the pans in hay boxes. For this experiment, using 4 liters of water I was aware that this small amount of liquor would cool quickly, perhaps too quickly? An experiment we conducted some years ago revealed that premature cooling of the extraction bath resulted in a dramatic loss of indigo when processing woad leaves. Two years ago we discovered that leaving the bath at a high temperature for more than one hour also results in a loss of indigo so I have become wary of putting large baths in hay boxes which are capable of maintaining a high temperature for hours.
In this second run the results from the white-flowered intermediate-leaved plant improved but the round-leaved plant still produced the better result (which itself was no better than in the first run).
Second run with intermediate white flowered indigo plant compared to rounded leaf plant.
Comparison of intermediate white flower strains. The difference between quick and slow cooling of the extraction bath.
No real difference between runs for the Rounded leaf strain.
In theory all three plants should have produced broadly similar amounts of indigo. That they did not could have been due to genetic differences but as noted above all three plants were at different stages of development having been planted at different times and the round-leaved strain had possibly adapted to the local soil over the 4/5 or so years I have been growing it. The poor results from the long-leaved plant may have been entirely due to their flowering state. The intermediate-leaved white-flowered strain had only been planted out in late August and may not have had sufficient exposure to the sun to develop much indigo.
The diversity of results shows how critical it is to grow and harvest the plant at the right time. I was certainly concerned that harvesting the plants in October was a risk, as all three varieties were producing flower buds (although only the long-leaved plants were in full flower). Later I extracted a concentrated bath of indigo by making up a large pan crammed full of leaves and only enough water to barely cover the leaves when they were pressed down forcibly. The results were pleasingly strong indicating that the leaves were still fully charged with indigo.
Skein on right dyed with a strong indigo dye bath
I will certainly be making strenuous efforts to continue to save the seed from the round leaf strain whatever the reasons for the underperformance of the other two strains!
Confirmation of results
Since this post Leena Riihelä writing in her blog (see Riihivilla) has confirmed that the long or pointed leaf variety of Japanese Indigo does not produce as much indigo as the broad or rounded leaf variety. Leena who also grew three strains of Japanese indigo this year also speculates that the broad leaf (rounded) variety originated in Japan. (The long leaf variety may come from Northern Japan or China). She is also able to confirm that the long leaf variety flowers much earlier. Leena is based in Finland which has such a short growing season that the rounded leaf variety does not have time to produce seed. Leena has a wealth of experience to share about indigo and other natural dyes so please visit her blog and web site. (see below)